feat: restore mentor page to final day/night spec

Rebuild the mentor workspace per the approved final design (day.png/night.png):
- mentorView gets a dedicated full-width immersive shell (independent 56px
  top bar with page title slot + theme mode text, hidden module-nav/market
  tape/overview/status bar) scoped to body[data-active-view=mentorView].
- Assistant messages become borderless body text with name/time above; only
  user messages use a blue bubble; keep loading/error/streaming caret states.
- 4 quick topics stay visible with history; composer restored to a framed
  ~94px card with bottom-left shortcut hint and bottom-right send button.
- Directory tools merged into one row (search + filter menu + sort); the
  filter menu still offers all/A/B/C; list selected state is an inset rounded
  fill; contact rows are borderless 75px items.
- Chat header always shows pin/note/profile/clear; pin reuses /api/mentors/
  preferences; theme toggle stays the single #themeToggle.
- Night tokens match the spec including the two distinct blues (#316FEF link,
  #5B8DEF quote/selected icon). Mobile (<768) stacks panels with no horizontal
  overflow; 1024+ follows the desktop spec.
- Update stale test baselines (300px sidebar, 94px composer, hint presence,
  night bubble color, centered disclaimer) and regenerate the architecture
  inventory.

Co-authored-by: multica-agent <github@multica.ai>

app/frontend/pages.config.js

@@ -47,7 +47,7 @@
     ["heaven", "/pages/heaven/page.html?v=20260803-1", ["heavenView"]],
     ["ladder", "/pages/ladder/page.html?v=20260803-1", ["ladderView"]],
     ["screener", "/pages/screener/page.html?v=20260804-1", ["screenerView", "screenerTrackingView"]],
-    ["mentor", "/pages/mentor/page.html?v=20260806-2", ["mentorView"]],
+    ["mentor", "/pages/mentor/page.html?v=20260818-1", ["mentorView"]],
     ["rotation", "/pages/rotation/page.html?v=20260803-1", ["rotationView"]],
     ["auction", "/pages/auction/page.html?v=20260803-1", ["auctionView"]],
     ["themes", "/pages/themes/page.html?v=20260803-1", ["themeLibraryView"]],
@@ -81,7 +81,7 @@
     "/pages/popularity/page.js?v=20260729-1",
     "/pages/dragon-tiger/page.js?v=20260806-1",
     "/pages/screener/page.js?v=20260806-1",
-    "/pages/mentor/page.js?v=20260806-2",
+    "/pages/mentor/page.js?v=20260818-1",
     "/pages/heaven/page.js?v=20260729-1",
     "/pages/review/page.js?v=20260729-1",
     "/shared/state.js?v=20260729-1",